1. Field
Example embodiments relate to a transistor and an inverter, and methods of manufacturing a transistor and an inverter.
2. Description of the Related Art
In semiconductor integrated circuits, e.g., dynamic random access memories (DRAM), static random access memories (SRAM), non-volatile memories, liquid crystal display devices, and organic light emitting devices, various logic circuits, e.g., NAND (not and) and NOR (not or) circuits, may be used. An inverter is the base of the logic circuits.
In general, a Si-based inverter is a complementary metal-oxide semiconductor (CMOS) including both an n-channel metal-oxide semiconductor (NMOS) transistor and a p-channel metal-oxide semiconductor (PMOS) transistor. When a Si layer is used as a channel layer, the NMOS or PMOS transistor may be easily formed by varying the type of doping elements for the channel layer, and thus, a CMOS inverter may be easily manufactured.
However, when a channel layer is formed using an oxide semiconductor, forming a p-channel layer due to the characteristics of the material in the oxide semiconductor may be difficult. In other words, a channel layer formed of an oxide semiconductor is usually an n-channel layer. Also, a transistor that may include an oxide semiconductor layer as a channel layer, for example, an oxide transistor, is usually a depletion-mode transistor having a threshold voltage of less than 0 V, and manufacturing an oxide transistor as an enhancement-mode transistor may be difficult. Accordingly, when an oxide semiconductor is applied to form a channel layer, manufacturing an inverter with desirable characteristics may be difficult.